On a recent trip to Penticton to meet up with a group of people interested in mosses and liverworts, I came across Hedwigia ciliata growing on a rock outcrop south of Penticton. Although it is not rare, it is an uncommon moss that I don’t see very often.

Superficially it resembles the much more common rock-moss (Racomitrium) which enhabits the same exposed sunny microsites on exposed rock.

It is similar to rock-moss in that it forms branching stems clothed in green to brown or blackish leaves with white hair points.

It differs though in that the leaves of Hedwigia lack a midrib whereas those of rock-moss have a midrib and often have a deep groove that runs along the center of the leaf.

I like the leaf cells of Hedwigia. They are short and thick and occur in orderly rows along the length of the leaves. The leaves show no trace of having a midrib.

There are three species of Hedwigia in North America which at one time were all considered to be the same species. However, Hedwigia stellata, which is the only one we have in the Southern Interior of BC, is distinguished from the other two species in that the leaf cells are covered in several small bumps called papillae whereas the other two species only have a single papilla per cell. Below you can see some of the papillae that occur on the cell wall of individual leaf cells.

The other distinctive feature of Hedwigia that distinguishes it from rock-moss and many other species is that the capsules have very short stalks and so the capsule remains buried in the surrounding leaves.

If you are looking at mosses on rock outcrops or cliff faces in open and exposed areas with a handlens, you are usually looking at any number of species of rock-moss or other species with white hair points. However, if you come across a branching multistemmed moss with leaves that have a white hair point and lack any hint of a groove or midrib on the leaves, then chances are you are looking at fringed hoar-moss.